LOS ANGELES — “Avatar” and “The Hurt Locker” have been duking it out all awards season. Now, the two films face their final showdown: They enter the 82nd annual Academy Awards prizefight with nine nominations apiece.

The films — which, coincidentally, are by former husband-and-wife James Cameron and Kathryn Bigelow — couldn’t be more different. “Avatar” is an eye-popping 3-D science-fiction studio extravaganza: It is the most expensive film ever made and has gone on to be the most successful film ever, earning more than $2 billion so far, worldwide. By contrast, “The Hurt Locker” is a gritty, low-budget, independent film about a bomb-disposal unit in the Iraq War. Though it has earned plenty of accolades this awards season, it has yet to crack the $13-million mark at the box office.

The films are two of the best picture nominees announced Tuesday morning by the Academy of Motion Picture Arts & Sciences, among an eclectic mix that included another sci-fi hit, “District 9,” another war film, “Inglourious Basterds” and the animated hit “Up,” which is only the second animated film ever to receive a nod in this category.

Though it was no surprise that “Precious: Based on the Novel ‘Push’ by Sapphire” and “Up in the Air” earned best picture nods, there were some unexpected choices, including “The Blind Side,” “An Education” and “A Serious Man.”

Noticeably missing from the best picture list was the summer blockbuster “Star Trek,” which some had thought would have a shot given the expanded best picture field and its recent Producers Guild of America nomination.

The academy’s announcement marked the first time in 66 years that there were 10 nominees in this marquee category, instead of the traditional five.

The nominees for best director were as expected. They included: Cameron for “Avatar,” Kathryn Bigelow for “The Hurt Locker,” Lee Daniels for “Precious,” Quentin Tarantino for “Inglourious Basterds” and Jason Reitman for “Up in the Air.”

But two of the nominees were nonetheless noteworthy: Bigelow, who won the Directors Guild of America Award over the weekend, is only the fourth woman to earn a best director nod. Daniels is just the second African-American filmmaker to earn that honor.

In the acting categories, the academy followed in the footsteps of the Golden Globes and the Screen Actors Guild Awards. The only real surprise was Maggie Gyllenhaal for best supporting actress for “Crazy Heart.” She had largely been overlooked this awards season.

The nominees for best actress were Sandra Bullock for “The Blind Side,” Helen Mirren for “The Last Station,” Carey Mulligan for “An Education,” Gabourey Sidibe for “Precious” and Meryl Streep for “Julie & Julia.” With this nod, Streep has earned an unprecedented 16 Oscar nominations over the last 31 years. She has received two Oscars: best supporting actress for 1979’s “Kramer vs. Kramer” and best actress for 1982’s “Sophie’s Choice.”

The best actor nominations went to Jeff Bridges for “Crazy Heart,” George Clooney for “Up in the Air,” Colin Firth for “A Single Man,” Morgan Freeman for “Invictus,” and Jeremy Renner for “The Hurt Locker.”

Joining Gyllenhaal in the best supporting actress category are Penelope Cruz for “Nine,” Vera Famiga and Anna Kendrick for “Up in the Air” and Mo’Nique for “Precious.” Cruz won in this category last year for “Vicky Cristina Barcelona.”

Nominated for best supporting actor are Matt Damon for “Invictus,” Woody Harrelson for “The Messenger,” Christopher Plummer for “The Last Station,” Stanley Tucci for “The Lovely Bones” and Christoph Waltz for “Inglourious Basterds.”

The nominations were revealed at 8:38 a.m. EST Tuesday at the academy’s Samuel Goldwyn Theater in Beverly Hills, with last year’s lead actress nominee Anne Hathaway helping Oscar president Tom Sherak with the announcements.

The Oscars will be telecast live March 7 on ABC from the Kodak Theatre in Hollywood.

Besides increasing its nomination list for best picture, the academy also is featuring two hosts at the Oscar ceremony: Alec Baldwin and Steve Martin, who just starred together in “It’s Complicated.”

The unfamiliar will only find acceptance if it is expressed in familiar terms; thus, aliens "...may have bulbous heads and triangular eyes, speak in a chillingly robotic monotone or emit a strong stench of sulphur, but otherwise they look much like Tony Blair."